Leptospirosis is among the world's most important zoonotic infectious diseases, annually affecting an estimated 868,000 people globally, with an estimated case fatality rate of 5-10%. Important gaps remain in translating recent fundamental molecular advances in studies of Leptospira and leptospirosis to public health approaches to preventing and ameliorating this infectious disease. The long-term goal of this project is to develop and validate new tools for the diagnosis of leptospirosis, in order to be able to address the true global burden of disease. In this study we propose to develop new field study sites in contrasting places to determine nationally as well as regionally important serovars (Aim 1). These studies will allow us to obtain well-characterized isolates to determine national and regional repertoire of Leptospira in a country of known diversity (Aim 2). The collaboration with Dr. Agampodi and the group in Sri Lanka will allow us to evaluate even more geographically distinct environments. Therefore this South-South collaboration build upon well-established scientific relationships is a key aspect of this project, in addition to the research capacity building and cross-disciplinary research outcomes. Lastly we propose to develop ultra-sensitive, broad-spectrum, rapid, inexpensive tests based on 1) high affinity monoclonal antibodies to lipopolisaccaride ; 2) antigen detection by using targets identified using protein arrays.